# Configuring EC2 server instances using the Amazon toolkit for Visual Studio
Amazon Elastic Compute Cloud (Amazon EC2) is a web service that you use to launch and manage server instances in Amazon's data centers. You can use Amazon EC2 server instances at any time, for as long as you need, and for any legal purpose. Instances are available in different sizes and configurations. For more information, go to [Amazon EC2](http://www.amazonaws.cn/ec2/).
You can edit the Elastic Beanstalk environment's Amazon EC2 instance configuration with the **Server** tab inside your application environment tab in the Amazon Toolkit for Visual Studio.
## Amazon EC2 instance types
**Instance type** displays the instance types available to your Elastic Beanstalk application. Change the instance type to select a server with the characteristics (including memory size and CPU power) that are most appropriate to your application. For example, applications with intensive and long-running operations can require more CPU or memory.
For more information about the Amazon EC2 instance types available for your Elastic Beanstalk application, see [Instance Types](https://docs.amazonaws.cn/AWSEC2/latest/UserGuide/instance-types.html) in the *Amazon Elastic Compute Cloud User Guide*.
## Amazon EC2 security groups
You can control access to your Elastic Beanstalk application using an *Amazon EC2 Security Group*. A security group defines firewall rules for your instances. These rules specify which ingress (i.e., incoming) network traffic should be delivered to your instance. All other ingress traffic will be discarded. You can modify rules for a group at any time. The new rules are automatically enforced for all running instances and instances launched in the future.
You can set up your Amazon EC2 security groups using the Amazon Management Console or by using the Amazon Toolkit for Visual Studio. You can specify which Amazon EC2 Security Groups control access to your Elastic Beanstalk application by entering the names of one or more Amazon EC2 security group names (delimited by commas) into the **EC2 Security Groups** text box.
**Note**
Make sure port 80 (HTTP) is accessible from 0.0.0.0/0 as the source CIDR range if you want to enable health checks for your application. For more information about health checks, see [Health checks](create_deploy_NET.managing.elb.md#create_deploy_NET.managing.elb.healthchecks).
**To create a security group using the Amazon toolkit for Visual Studio**
1. In Visual Studio, in **Amazon Explorer**, expand the **Amazon EC2** node, and then double-click **Security Groups**.
1. Click **Create Security Group**, and enter a name and description for your security group.
1. Click **OK**.
For more information on Amazon EC2 Security Groups, see [Using Security Groups](http://docs.amazonaws.cn/AWSEC2/latest/UserGuide/using-network-security.html) in the *Amazon Elastic Compute Cloud User Guide*.
## Amazon EC2 key pairs
You can securely log in to the Amazon EC2 instances provisioned for your Elastic Beanstalk application with an Amazon EC2 key pair.
**Important**
You must create an Amazon EC2 key pair and configure your Elastic Beanstalk–provisioned Amazon EC2 instances to use the Amazon EC2 key pair before you can access your Elastic Beanstalk–provisioned Amazon EC2 instances. You can create your key pair using the **Publish to Amazon** wizard inside the Amazon Toolkit for Visual Studio when you deploy your application to Elastic Beanstalk. If you want to create additional key pairs using the Toolkit, follow the steps below. Alternatively, you can set up your Amazon EC2 key pairs using the [Amazon Management Console](https://console.amazonaws.cn/). For instructions on creating a key pair for Amazon EC2, see the [Amazon Elastic Compute Cloud Getting Started Guide](http://docs.amazonaws.cn/AWSEC2/latest/GettingStartedGuide/).
The **Existing Key Pair** text box lets you specify the name of an Amazon EC2 key pair you can use to securely log in to the Amazon EC2 instances running your Elastic Beanstalk application.
**To specify the name of an Amazon EC2 key pair**
1. Expand the **Amazon EC2** node and double-click **Key Pairs**.
1. Click **Create Key Pair** and enter the key pair name.
1. Click **OK**.
For more information about Amazon EC2 key pairs, go to [Using Amazon EC2 Credentials](http://docs.amazonaws.cn/AWSEC2/latest/UserGuide/using-credentials.html) in the *Amazon Elastic Compute Cloud User Guide*. For more information about connecting to Amazon EC2 instances, see [Listing and connecting to server instances](create_deploy_NET.ec2connect.md).
## Monitoring interval
By default, only basic Amazon CloudWatch metrics are enabled. They return data in five-minute periods. You can enable more granular one-minute CloudWatch metrics by selecting **1 minute** for the **Monitoring Interval** in the **Server** section of the **Configuration** tab for your environment in the Amazon Toolkit for Eclipse.
**Note**
Amazon CloudWatch service charges can apply for one-minute interval metrics. See [Amazon CloudWatch](http://www.amazonaws.cn/cloudwatch/) for more information.
## Custom AMI ID
You can override the default AMI used for your Amazon EC2 instances with your own custom AMI by entering the identifier of your custom AMI into the **Custom AMI ID** box in the **Server** section of the **Configuration** tab for your environment in the Amazon Toolkit for Eclipse.
**Important**
Using your own AMI is an advanced task that you should do with care. If you need a custom AMI, we recommend you start with the default Elastic Beanstalk AMI and then modify it. To be considered healthy, Elastic Beanstalk expects Amazon EC2 instances to meet a set of requirements, including having a running host manager. If these requirements are not met, your environment might not work properly.